I think As long as the system has to buy altcoin using bitcoin / eth, it is very unlikely altcoin will go beyond bitcoin, because there will be people who put as much money into BTC as they do.
Because Altcoin is generally just a bigger market, but for the most part, bitcoin is the bridge between them. Generally, if you want to buy altcoin, you should buy bitcoin and then use the bitcoin to buy alts. It's hard to find a place to buy altcoin directly. I believe this is what makes Bitcoin and Ethereum especially so great in terms of all other altcoins.